Yet earlier this week, theblogosphereexploded with declarations that the Material Girl had ascended to billionaire status. Most of the stories erroneously cited a WWD story as the source of this revelation (representatives from the publication confirm that no such piece exists), probably because of a New York Post item that initially linked to WWD before shifting its attribution to another site.

We estimated the singer's net worth at $325 million six years ago. Since then, our wealth team has chronicled the scads of cash she's earned via our Celeb 100 list, and while she’s earned a ton of money, the numbers don't add up to anything near $1 billion. She earned $72 million in 2007, $40 million in 2008, $110 million in 2009 and $58 million in 2010. With no touring or new albums in 2011, she didn't earn enough to make our list that year, then pulled in another $30 million through the first half of 2012.

Add it all up (plus whatever she earned in 2011--let's call it $10 million) and you get $320 million. Lop off 35% for federal income taxes ($112 million), another 10% for state and local taxes ($32 million) and 20% for management, legal and agency fees ($64 million). That leaves $112 million before figuring in any expenses for housing, staff, travel or luxury goods.

What about that big concert tour? Most of the recent reports have mentioned Madonna's past 12 months as the reason for her ascent into the financial pantheon, citing sales of her MDNAalbum and a world tour that grossed just over $300 million. They mention perfume sales of $60 million, tour merchandise sales of $75 million, and other branding deals that add up to $30 million.

But the difference between gross ticket sales, gross earnings and net earnings is ignored. Artists typically take home about one-third of gross ticket sales on the road--in Madonna's case, that means $300 million becomes $100 million.

To gross $75 million in merchandise sales, she would have had to average sales of $34 per head on her tour (or about $10 more than Justin Bieber). And that's just the gross number. For most artists, we project net earnings of $5 per head for merch; Bieber's take tops the charts at about $10, according to his touring team. Let's give Madonna the benefit of the doubt and say that she also nets $10 per head--over the course of a tour that drew 2.2 million fans, that would have added up to $22 million in take-home pay.

Madonna's record deal guarantees her a base advance of $1 million per album, but MDNA hasn't likely earned much more than that. It's been certified gold in the U.S. for sales of over 500,000, and it seems likely the album has sold at least as many copies abroad. Still, that's only a little more than a million copies sold, resulting in just a few million dollars in her coffers--about the same amount that most A-list entertainers net from perfume deals, regardless of heady gross sales.

But let's be overly generous. Let's say Madonna earned $200 million over the past year. Take away 65% for taxes and management fees, as we did before. That leaves $70 million. Combine that with the $112 million left over from 2007 through the first half of 2012, and you get $182 million. So even if Madonna had saved every single penny she'd earned since 2007--no travel costs, no living cost, no splurges--she'd be worth about $500 million.

Is it possible that she has other assets that have increased in value and therefore wouldn't be figured into our annual earnings estimates? Sure. Her real estate holdings, art collection and stakes in other business ventures could have increased. But keep in mind that 2007 was the peak of a long bull market; assets that lost value during the recession are only now returning to those highs.

Madonna's representatives wouldn't respond to FORBES' requests for comment on this story, as it seems was the case with all the stories about her net worth published over the past week. And this isn't the first time FORBES has weighed in on inflated claims about the singer's billionaire status--staff writer Clare O'Connor debunked one set back in 2010.

Madonna is a cultural icon, and undoubtedly one of the most successful entertainers of all time. She may well reach the billion-dollar mark one day. But as of now, at best, she's only about halfway there.